Viewing a graphical representation of an access plan - IBM DB2 9.7 for Linux, UNIX, and Windows

Use the Access Plan Graph window to view a graphical representation of the access plan of an explained SQL or XQuery statement.

About this task

The nodes in the graph represent tables and indexes and each operation on them. The links between the nodes represent the flow of data.

Tasks

Use the Statement menu to print the graph, to dynamically explain an SQL or XQuery statement, to view the text or optimized text, or to view optimization parameters or statistics.
Use the Node menu to view details or statistics on the nodes, or to get additional help on each of the operators.
Use the View menu to change the graph settings or to see an overview of the graph. This is particularly useful for large graphs.

From this window, you can view details about the following objects:

Table spaces and table space statistics
Functions and function statistics
Operators
Partitioned databases
Operands
- Column distribution statistics
- Index and index statistics
- Page fetch pairs statistics
- Column groups
- Referenced columns, referenced column groups, and referenced column statistics
- Table function statistics and table statistics

To open the Access Plan Graph window, use one of the following methods:

Open either the Explainable Statements, or the Explained Statements History window. Select Statement > Show Access Plan. The Access Plan Graph window opens.
Invoke Explain Query from either the Explainable Statements or the Explained Statements History window. The Explain Query statement window opens as a result of the dynamic explain.

Reading the contents of the Access Plan Graph window

Top area of the window

The top area of the Access Plan Graph window identifies the statement whose access plan is displayed on the graph.

This part of the window also shows:

The statement's explain date, time, package name, and version.
If the Federated function was enabled at the time the statement was created.
Its total estimated cost.
The type of parallelism of the system in which this statement is explained. It can be one of the following types:
- None
- Intra-partition parallelism
- Inter-partition parallelism
- Full parallelism (intra-partition and inter-partition)

The graph

The nodes in the graph represent operands (tables, indexes, or table functions), and the operators that act on them. To view detailed statistical information for a node, double-click on it.

To view the information shown in the graph in more detail, drag the zoom slider up or down.

Float values might be presented in scientific notation.

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